Feed preservation



NOV. 17, 1953 A Q AV FEED PRESERVATION Filed April 16, 1949 Patented Nov. 17, 1953 FEED PRESERVATION Ausie Calaway Eaves, Brawley, Calif., assignor to Ralston Purina Company, St. Louis, Mo., a corporation of Missouri Application April 16, 1949, Serial No. 87,933

7 Claims. (01. 34-31) This invention relates to feed preservation and more particularly to the preservation of alfalfa.

Briefly, the present invention comprises methods for treating alfalfa to preserve the carotene content thereof by first exposing alfalfa to a flow of heated air and thereafter exposing said alfalfa to a further flow of heated air directed oppositely to said first air flow. This invention also includes methods for treating alfalfa which comprises exposing alfalfa to a flow of air heated to a temperature of at least approximately 180 F., the specific humidity of which is not greater than that of saturated air at 158 F. The invention further comprises apparatus suitable for carrying out the above specified methods.

Among the several objects of this invention are the provision of apparatus for the preservation of feed, which dehydrates alfalfa with a minimum loss of carotene at a high production rate; the provision of methods of dehydrating feeds which produce dehydrated products at low cost With a minimum loss of carotene; the provision of methods of preserving feed which produce dehydrated feed of high and uniform quality which retains a large proportion of its original carotene content; and, the provision of apparatus of the class described which is rugged in construction and simple and efficient in operation. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, steps and sequence of steps, features of construction and manipulation, and arrangements of parts which will be exemplified in the structures and methods hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a diagrammatic representation of the dehydration apparatus of the present invention;

Fig. 2 is a plan view of one embodiment of the dehydration apparatus of the present invention; and,

Fig. 3 is a front elevation view of the apparatus of Fig. 2, with parts broken away. I

Similar reference characters indicate corresponding parts throughout the several views of the drawing.

The use of dried alfalfa both as an animal and poultry feed and as a basic ingredient in many animal feeds has long been established as being beneficial to animal health. However, the full food values of freshly cut alfalfa have not been retained in the dried product. This is primarily due to diminution of the carotene content of the alfalfa during drying and storage. This loss may be due to the deleterious effects of oxidation, sunlight, enzymatic action, and high temperatures, as well as other conditions which may adversely affect carotene. The carotene'content of alfalfa decreases from the time it is out until it is fed to the animal in its final dehydrated form and. the longer the storage period the greater is the loss, under usual conditions.

It has been found in accordance with the present invention that excessive diminution of carotene can be avoided and dried alfalfa can be produced which possesses a large proportion of the carotene originally present and which will retain high percentages of the original carotene content even after extensive periods of storage. The alfalfa either freshly cut or after a period of sun drying is subjected to a flow of air heated to a temperature of at least F. and thereafter is exposed to a second flow of heated air directed against the partially dried alfalfa in a direction opposite to that of the initial air flow. Thetemperature of the heated air stream directed against the freshly cut alfalfa is maintained above 180 F., but below that which would scorch or burn the alfalfa. The specific humidity is maintained below the value at which air becomes saturated at 158 F. Novel apparatus has also been devised which operates to efliciently expose the alfalfa to heated air and automatically and continuously transfer such partially dried alfalfa to a low temperature dehydration section. Operation of this apparatus in accordance with the methods hereinafter described insures high capacity production of dehydrated alfalfa at minimum cost and with minimum loss in carotene content. 7 Referring now more particularly to Fig. 1 of the drawing, there is indicated generally at numeral l a feeding section of a two zone dehydrator 3. Dehydrator 3 comprises a primary zone 5 and a secondary zone 1 which operate 00- operatively to continuously dehydrate a forage crop unloaded into section The feeding section I includes a tilting hydraulic platform 9 for intermittently dumping loads of alfalfa or the like into an unloading pit l I, and a continuously moving endless belt feeder l3 which operates to elevate the feed and move it toward primary zone I. Mounted above feeder I3 is a top rake l4 and a spiked kicker l5 which serve to maintain a substantially constant flow of alfalfa to a continuously moving endless mat I? which begin in a second pit [9. Mat ll traverses the entire length of both zones 5 and 7 of the dehydrator 3 and has mounted above it a second kicker it, an adjustable leveling rake 2|, and an adjustable hold-down mat 23.

Mat 23 is mounted above and contiguous to mat i! and extends through substantially the entire length of primary'zone 5'. A baflie 25 separates zone 5 from zone 1. Bafile 25 has an aperture 26 of sufiicient size to pass only mat l! and the alfalfa layer carried thereon. Mat 1:? terminates at the end of zone 1 and there drops partially dehydrated alfalfa onto the surface ofanintermediate mat 21 mounted below and contiguous mat ll. A swinging baffle 28 prevents air from passing over the left end of mat t1 without passing through the alfalfa layer thereon. Mat 2! is driven so as to move in the oppositedirection to mat I! so as to deposit alfalfa at a later stage of dehydration on the top surface of a lower mat 29, which is mounted below and parallel mat 21 and which moves the alfalfa again in the same direction as mat fl and discharges fully dehydrated alfalfa throu h a discharge opening 3!. Mats ll, 23; 2'1 and 29' are formed of perforateor foraminous material such as wovenwire of 3 to mesh.

Referring now more particularly to Figs. 2 and 3 the construction of the dehydrator unit i is shown in more detail together with the air circulation therethrough. Mounted on top of and extending over substantially the entire zone I is an input manifold 33 having an inlet duct 35- which is connected to any conventional source (not shown) of hot dry air. lvlanifold 33 may include various baiiies adapted to deflect the incoming air into paths which insure relatively evenpassage of the air downwardly through all portions of mat i1 within zone 1. Several outlet apertures 3'! are formed in the lower side wall of zone I and serve as communication between the interior of zone 1' and anexhaust manifold 39. The path of the air through zone 1 is substantially vertically downward through all three mats PT, 21 and 29 as indicated in Fig. 3-. Additional baflies may also be interposed between the mate to insure vertical flow of the air.

Moist, cooled air is exhausted from manifold 39 through ports 40 to the atmosphere and through a duct 4| to the top section 42 of a secondary manifold; 43-. Thus; a portion of the exhaust air from zone T is vented to the atmosphere and the balance is passedthrou h duct M to the top section 42- of secondary manifold 43. A duct interconnects manifold section 42 to a blower fan 41. Fan 4'! feeds a furnace unit 49 which in turn is interconnectedto zone 5 throu h the bottom section of secondary manifold 43 and a duct 5|. The reheated air leaving furnace 49 comprises a portion of the exhaust air stream from zone I, a quantity of fresh air which is admitted through an aperture 44 in duct 45', and the products of combustion from furnace 49 which include fresh air drawn into the furnace through an aperture 4-5 for purposes of combustion. This reheated air is then passed upwardly through mat I! and the alfalfa carried thereon so as to heat and partially dry the alfalfa passing through zone 5. The air is thereafter exhausted through a screen covered outlet 53. Baflies may be mounted within zone 5 to insure substantially even flow of the heated air upwardly through all portions of mat ll within zone 5.

A swinging bafiie 51 is mounted above mat H as it enters zone 5 so as to prevent leakage of air from zone 5 other than through outlet 53.

Operation is as follows:

A truck 6 loaded with freshly cut or partially sun dried alfalfa is driven on the platform 9 which is then tilted to dump the alfalfa into pit H wherein it is elevated by belt 13. Top rake I4, is driven in a counterclockwise direction so as to insure a continuous alfalfa layer of predetermined thickness being fed into pit l9. Kicker l5 rotates in a clockwise direction and serves to fluff the alfalfa as it falls into pit i9. Kicker i8 also rotates clockwise and further insures proper and even dispersal of the alfalfa upon belt ll. Belt IT is thus continuously and evenly loaded alfalfa which is fed in a layer upwardly into zone 5. Leveling rake 2| rotates counterclockwise and is adjusted to give a layer of alfalfa of desired thickness. Hold down mat 23 is also adjustable. to any desired height above mat ii" and serves to prevent alfalfa fragments from; being blown upward and out of the zone 5.. lihe mat; speeds may be conveniently varied. in accordance with ambient temperatures and the condition of the alfalfa.

The alfalfa then is carried through aperture into zone i where it is exposed to the downwardly directed flow of hot dry air from manifold 33. At" the left end of mat I? the partially dehydrated alfalfa tumbles: onto the surface of mat 2? which moves it to the right toward baffle 25. At the end of mat 2?. the alfalfa gravitates' to the surface of mat 2a where it is moved to the exit 3! and thereafter discharged for further processing, such as grinding and packaging.

The air which enters zone 1 through manifold 33 picks up sufiici'ent quantities of water to insure that the alfalfa leaving zone i isdehy' drated to such an extent that it has a water content less than approximately 10% and preferably approximately only 5-170 The air during its passage through zone 'f' has been cooled and picks up moisture. A portion of this air is then 1 passed through duct ii to fan 41' and then re heated by furnace 45 and fed into zone 5 through secondary manifold 43. The balance of the effluent air from zone 5 is vented to the atmosphere through ports 46-. The reheated air is forced upwardly through the alfalfa layer travelling through zone 5. This layer is held between mat ll and hold down mat 23; the latter moves at the same-rate of speed and in the same direction as mat H. The reheated air after passing through the alfalfa layer in zone 5 is discharged to the atmosphere through outlet 53.

The following examples are illustrative only.

Example 1' Cut alfalfa was fed onto mat l! and relatively dry air was fed into manifold 33 at a temperature of about 350 F. Approximately /4 of the effluent air from exhaust manifold 59' was vented directly to the atmosphere through ports 48- and the remaining A; was reheated by furnace 45 to a temperature of approximately 350 F. The moisture content of this reheated air was maintained below approximately 1.8% relative humidity at 350 F.

Dehydrated alfalfa was produced at the rate of 5.8 tons per hour. The carotene content of the alfalfa at exit 3! was found to be 341 p. p. m. The initial carotene content of the chopped alfalfa was found to be 372 p. p. in. Thus, the dehydration of the alfalfa was accomplished with a carotene retention of 91.8%.

Example 2 Example 1 was repeated with alfalfa havin a carotene content of approximately 341 p. p. m. at the beginning of mat ll. The carotene content of the dehydrated alfalfa was 314 p. p. m., giving a carotene retention of 92.1%.

Example 3 Example 1 was repeated with alfalfa having a carotene content of approximately 322 p. p, m. at the beginning of mat IT. The carotene content of the dehydrated alfalfa was 311 p. p. m., giving a carotene retention of 96.6%.

Example 4 Example 1 was repeated with alfalfa having a carotene content of approximately 351 p. p. m. at the beginning of mat H. The carotene content of the dehydrated alfalfa was 329 p. p. m., giving a carotene retention of 93.2

It is to be understood that the thickness of the layers and the rate of movement through zones 5 and I may be varied considerably depending on ambient temperature and humidity conditions and upon the initial moisture content of the chopped alfalfa. Similarly the temperatures of the air flowing through zone 5 and zone I may be varied from the values given.

It is also to be noted that proportions of air from zone 1, other than A, may be reheated and fed into zone 5. In fact, air from an exterior source may be used exclusively rather than preheating portions of eliluent air from zone 5, as long as the temperatures and moisture content are properly controlled. Under preferred operating conditions approximately /3 of the total moisture is eliminated in zone 5 and the average temperature of the alfalfa layer entering zone I is approximately 125 F. The temperature of the alfalfa layer entering zone 1 from zone 5 is maintained between limits of between approximately 100 F. and approximately 158 F. The specific humidity of the input air to zone 5 must be maintained below that of saturated air at 158 F.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. The method of dehydrating alfalfa which comprises passing heated air through a mass of alfalfa for a period of time suflicient to heat alfalfa to a temperature of between approximately 100 F. and 158 F., said air having a specific humidity not more than that of saturated air at 158 F., and thereafter passing a further quantity of heated air through said alfalfa for a period of time sufiicient to reduce the moisture content of said alfalfa to a value below approximately said further quantity of air having a temperature not substantially in excess of 350 F.

2. The method of dehydrating alfalfa which comprises exposing alfalfa to a continuous flow of air heated to a temperature above approximately 180 F. and having a specific humidity not more than that of saturated air at 158 F. for a period of time suificient to heat alfalfa to a temperature of between approximately F. and 158 F., and thereafter exposing said alfalfa to a continuous flow of heated air having a temperature not substantially in excess of approximately 350 F. for a period of time sufficient to reduce the moisture content of said alfalfa below a value of approximately 10%.

3. The method of dehydrating alfalfa which comprises passing air heated to a temperature of at least approximately 180 F. through a mass of alfalfa for a period of time sufiicient to heat alfalfa to a temperature of between approximately 100 F. and 158 F., said air having a specific humidity not more than that of saturated air at 158 F., and thereafter passing heated air directed oppositely to that of said first heated air through said alfalfa for a period of time suificient to reduce the moisture content of said alfalfa to a value below approximately 10%, the last said heated air having a temperature not substantially in excess of 350 F.

4. The method of dehydrating alfalfa which comprises passing air heated to a temperature of at least approximately 180 F. through a mass of alfalfa for a period of time sufficient to heat alfalfa to a temperature of between approximately 100 F. and 158 F., said air having a specific humidity not more than that of saturated air at 158 F., and thereafter passing a further quantity of heated air in a direction counter to that of the first said heated air through said alfalfa for a period of time suflicient to reduce the moisture content of said alfalfa to a value below approximately 10%, said further quantity of air having a temperature not substantially in excess of 350 F.

5. The method of dehydrating alfalfa which comprises passing heated air through a mass of alfalfa for a period of time sufficient to heat alfalfa to a temperature of between approximately 100 F. and 158 F., said air having a specific humidity not more than that of saturated air at 158 F., and thereafter passing heated air through said alfalfa in a direction opposite to that of said first heated air for a period of time sufficient to a reduce the moisture content of said alfalfa to a value below approximately 10%, the first said heated air being supplied at least in part by reheating a portion of the last said heated air after it has passed through said alfalfa, the last said heated air having an initial temperature not substantially in excess of 350 F.

6. The method of dehydrating alfalfa which comprises moving alfalfa through a first zone in contact with air heated to a temperature in excess of about 180 F. for a time suflicient to heat alfalfa to a temperature of between approximately 100 F. and 158 F., said air having a specific humidity not more than that of saturated air at 158 F., and thereafter moving said alfalfa through a second zone in a series of contiguous oppositely moving passes while in contact with heated air for a time sufficient to reduce the moisture content of said alfalfa to a value below approximately 10% the first said heated air being supplied at least in part by reheating the eiiiuent air from said second zone, the second said heated air having an initial temperature not substantially in excess of 350 F.

7. The method of dehydrating alfalfa which comprises moving alfalfa through a first zone, passing heated air upwardly through said alfalfa 7,- ior at oi time suficient, to heat alfalfa to atemperatuxe of approximately 125 R, said heated having a.,tempe1:atume of approximate- 13; 3.50 E; amt a relative" humidity of not more approximately 1.8%, moving; said. alfalfa through a. second zone in a series; of contiguoue oppositely moving passes, passing heated air downwardly through said alfalfa in the second zone; for at time sufficient to reduce. the moisture content of said alfalfa to: a value of approximately 5%; ta 7%}, the first said. heated air being supplied. at; leastin part by reheating approximately one; quarter of. the. eflluent air from said second zone, the sexzondsaid. heated air having an initial temperature of approximately 350?" E.

AUSIE CALAWAY EAVES;

References. Cited! in the file of this patent UNITED STATES PATENTS Number Name Date Davidson Dec. 20, 1898 Goodwin Feb. 18, 1902 Roth Oct. 12, 1909 Rich July 21, 1914 Goubert June 3, 1919 Bennett Apr. 2, 1929 Fulmer Jan. 6, 1931 Randolph Nov. 23, 1937 Fulmer Nov. 8, 1938 Wayland June 29, 1943 Chilton May 30,1944 

